Physical address alternatives
Legally you're obligated to include a physical address in every email you send (CAN-SPAM). That's often not an issue if you run a physical store or have an office, but if you run your store from home or remotely, it probably won't be ideal to include your home address in every email.
Fortunately, you have a few alternatives.
Ask a friend with a business if you can use their address.
Rent a P.O. Box. You can normally do this at your local post office for around $100-$200 per year.
Try your local UPS store. Sometimes they'll allow you to set up a PO Box without having an actual PO Box address, but rather a suit #, that will direct the mail to you. the mail for you to the right box. Prices vary depending on the store so call your nearest location for details.
Use a Commercial Mail Receiving Agent.
If you work out of a co-working space, ask them if you're able to use their address.